I've called Dell yesterday and before they send me a tech to fix it at home, they need me to call the support line -- which is not free -- and reformat my computer following their instructions and then go through a serie of tests, etc. They don't seem to believe me when I say it's the hard drive that's responsible since I told them (because they asked) that Dell's diagnostic utility passed all tests. Oh and the only way I can get my money back (from the non toll-free line) is if they admit my hard drive is broken. That's complete bs and I'm actually ........ed at them.

Dell wouldn't do anything more unless I format my hard drive and so I did. It's considerably faster and I would consider it as running at a normal pace right now. I don't know if this is a temporary fix or permanent fix but it did the job.